When cutting or engraving acrylic you will often get "smoke-round" around the cut or engraved areas. Sure you can remove this with Isoprop but cleaning several hundred small parts can be a pain in the butt.
Quick cure that all but eliminates it is a cheap can of silicon oil (Lidl have them at 99p for 500ml)
spray the surface of your sheet (both sides) and allow to dry (30 seconds) before putting it in the laser, run the job then simply wash your parts with fairy liquid afterwards to remove any trace of silicon
Hey presto the smutt-smoke doesn't stick
did get some funny looks at Lidl when I went in and bought 100 cans though
best wishes
Dave